Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Nitrogen or nitrogenous component
Reexamination Certificate
2005-08-02
2005-08-02
Langel, Wayne A. (Department: 1754)
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Nitrogen or nitrogenous component
C423S244020
Reexamination Certificate
active
06923945
ABSTRACT:
The present invention relates to a layered catalyst composite useful for reducing contaminants in exhaust gas streams, especially gaseous streams containing sulfur oxide contaminants. More specifically, the present invention is concerned with improved catalysts of the type generally referred to as “three-way conversion” catalysts. The layered catalysts trap sulfur oxide contaminants which tend to poison three-way conversion catalysts used to abate other pollutants in the stream. The layered catalyst composites of the present invention have a sulfur oxide absorbing layer before or above a nitrogen oxide absorbing layer. The layered catalyst composite comprises a first layer and a second layer. The first layer comprises a first support and at least one first platinum component. The second layer comprises a second support and a SOxsorbent component having a free energy of formation from about 0 to about −90 Kcal/mole at 350° C. The sulfur oxide absorbing layer selectively and reversibly absorbs sulfur oxides over nitrogen oxides and prevents or alleviates sulfur oxide poisoning of the nitrogen oxide trap.
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Engelhard Corporation
Langel Wayne A.
Negin Richard A.
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